Bi-directional pressure relief valve

Abstract

A bi-directional pressure relief valve includes a cylindrical main body portion defining a flow path through the valve and terminating in an asymmetrical lip portion having a curved contour about an axis of curvature extending perpendicularly to the flow path and a linear contour which is substantially normal to the curved contour. The lip portion has a normally closed slit formed through it and expands to open the slit to permit flow in one direction in response to pressure differentials across the lip portion above a first pressure differential, regains its undeformed shape to close the slit and check flow at pressure differentials below the first differential and above a second pressure differential, and collapses in a predictable and repeatable manner to open the slit to permit flow in an opposite direction at pressure differentials below the second pressure differential. A preferred embodiment includes an annular flange formed about the lip portion which facilitates the mounting of the valve in a conduit. If desired, the pressures at which flow can occur through the valve may be increased by providing the valve with stiffening ribs projecting radially outwardly of the main body portion.

What is claimed is: 
     
       1. A bi-directional pressure relief valve comprising: a substantially cylindrical main body portion having a central longitudinal axis and defining a flow path through said valve;   said cylindrical main body portion terminating at one end thereof in a lip portion;   said lip portion having a curved contour about an axis of curvature extending substantially perpendicularly to and intersecting said central longitudinal axis;   said lip portion having a linear contour perpendicular to said central longitudinal axis such that said lip portion is radially asymmetrical about said central longitudinal axis;   at least one normally closed slit formed in said lip portion; and   said main body and lip portions being formed of elastomeric material such that said slit opens to permit flow through said lip portion in a forward direction at or above a first predetermined pressure level, closes to check flow through said lip portion at pressures between said first pressure level and a second predetermined pressure level, and said lip portion collapses, thereby opening said slit and permitting reverse flow through said lip portion at reverse flow pressures greater than said second pressure level.   
     
     
       2. The valve of claim 1 wherein said linear contour lies in a plane which is normal to a second plane containing said curve contour. 
     
     
       3. The valve of claim 2 wherein said slit extends along said curved contour. 
     
     
       4. The valve of claim 2 wherein said slit extends along said linear contour. 
     
     
       5. The valve of claim 3 or 4 wherein said slit intersects said central longitudinal axis. 
     
     
       6. The valve of claim 5 wherein said slit is radially symmetric with respect to said central longitudinal axis. 
     
     
       7. The valve of claim 6 wherein said curved contour is of substantially constant radius of curvature from said axis of curvature. 
     
     
       8. The valve of claim 7 further comprising means defining a flange extending about said lip portion and integral with said main body portion. 
     
     
       9. The valve of claim 4 further comprising stiffening means associated with said main body portion for increasing at least said first pressure differential. 
     
     
       10. The valve of claim 9 wherein said stiffening means comprises rib means extending along said main body portion. 
     
     
       11. The valve of claim 10 wherein said rib means are molded integrally with said main body portion. 
     
     
       12. The valve of claim 11 wherein said rib means project radially outwardly of said main body portion. 
     
     
       13. The valve of claim 12 wherein said rib means comprise a pair of diametrically positioned ribs. 
     
     
       14. A bi-directional pressure relief valve comprising: a substantially cylindrical main body portion having a central longitudinal axis and defining a flow path through said valve;   said cylindrical main body portion terminating at one end thereof in a lip portion;   said lip portion having a curved contour of constant radius of curvature about an axis of curvature extending substantially perpendicularly to and intersecting said central longitudinal axis;   said lip portion having a linear contour perpendicular to said central longitudinal axis and parallel to said axis of curvature such that said lip portion is radially asymmetrical about said central longitudinal axis;   at least one normally closed slit formed in said lip portion and intersecting said central longitudinal axis; and   said main body and lip portion being formed of elastomeric material such that said slit opens to permit flow through said lip portion in a forwad direction at or above a first predetermined pressure level, closes to check flow through said lip portion at pressures between said first pressure level and above a second predetermined pressure level, and said lip portion collapses, thereby opening said slit and permitting reverse flow through said lip portion at reverse flow pressures greater than said second pressure level.